Engineering Economics. Don't guess if u don't know it. Do bot answer

In 1990, Mrs. John Hay Whitney sold her painting by Renoir, Au Moulin c/e la Galette, depicting an open-air Parisian dance hall, for $71 million. The buyer also had to pay the auction house commission of 10% or a total of $78.1 million. The Whitney family had purchased the painting in 1929 for $165,000. Determine the real rate of return that the Whitney family received if the inflation rate is 3.5%